Magnet, attaching device, attaching arrangement and method for attaching to an object

ABSTRACT

The invention relates to a magnet, which comprises a first permanent magnet for creating a magnetic field, and a shell and a centre, which are arranged to guide a magnetic flux to an object to be gripped. The magnet further comprises a slide, which is arranged to be movable in relation to the shell and the centre, which slide comprises said first permanent magnet, and an electric magnet for moving the slide. The invention also relates to an attaching device, and attaching arrangement and a method for attaching to an object.

TECHNICAL FIELD OF THE INVENTION

The invention relates to a magnet and a method for attaching to an object according to the preambles of the independent claims presented hereafter. The invention further relates to an attaching device and an attaching arrangement, by means of which an object, such as for example an object to be worked or a working base, may be gripped.

PRIOR ART

Devices intended for lifting and moving an object generally use magnets, by means of the holding force of which an object is gripped. The devices use one or several magnets, which may either be permanent magnets or electric magnets. A problem with a permanent magnet is that its holding force cannot be adjusted and it is difficult to detach it from the object. The holding force of an electric magnet may be adjusted by altering the electric current travelling through a coil of the electric magnet. A problem with the electric magnet is however that maintaining the holding force consumes electric energy.

OBJECT AND BRIEF DESCRIPTION OF THE INVENTION

It is an object of the present invention to among others reduce or even eliminate the above-mentioned problems appearing in the prior art.

It is an object of the present invention to provide a magnet, an attaching device, an attaching arrangement and a method, which may easily and quickly be used to grip an object and detach from it. It is further an object of the invention to provide a magnet, an attaching device, an attaching arrangement and a method, which consume as little electric energy as possible.

The above-mentioned disadvantages can be reduced or even completely eliminated, and the above-defined objects are attained with the present invention, which is characterised in what is defined in the characterising parts of the independent claims presented further below. Some preferred embodiments according to the invention are disclosed in the dependent claims presented further below.

The embodiments and advantages mentioned in this text apply, when applicable, both to the magnet, the attaching device, the attaching arrangement, the method and other objects of the invention according to the invention, even though it is not always specifically mentioned.

A typical magnet according to the invention comprises a first permanent magnet for creating a magnetic field, and a shell and a centre, which are arranged to guide the magnetic flux to an object to be gripped. A typical magnet according to the invention comprises a slide, which is arranged to be movable in relation to the shell and the centre and which comprises said first permanent magnet. A typical magnet according to the invention further comprises an electric magnet for moving the slide.

In the magnet according to the invention the slide is arranged to be movable in relation to the rest of the magnet between a holding position and an open position, in order to close and open the circuit of the magnetic flux. The slide is moved in relation to the shell and centre by means of a magnetic field provided with the electric magnet.

In the holding position the slide stays in contact with the shell and centre with permanent magnetic force, maintaining the part of the closed circuit of the magnetic flux, which is inside the magnet. Typically the object to be attached to the magnet, such as for example the object to be worked or the working base, forms the part of the closed circuit of the magnetic flux, which is outside the magnet. The parts of the shell and centre meant to be in contact with the object to be gripped form the differently named poles of the magnet. The centre is typically arranged inside an area delimited by the shell. The coil of the electric magnet is typically arranged around the centre and attached to the shell. The shell advantageously comprises a cylindrical through-hole, inside which the centre and the electric magnet are arranged.

When electric current is led to the coil of the electric magnet in a certain direction, the magnetic field produced by the electric magnet weakens the magnetic field of the permanent magnet. At a certain strength of the magnetic field the slide detaches from the shell and centre, whereby the closed circuit of the magnetic flux breaks, the magnetic force weakens and the magnet is switched off, i.e. the hold of the magnet is off. The hold of the magnet detaches from both poles of the magnet at the same time.

The hold of the magnet is switched on so that electric current is led into the coil of the electric magnet in the opposite direction to when the hold is detached. The electric current is thus guided in the direction of the coil, which strengthens the magnetic field of the permanent magnet. Now the magnetic field of the coil starts to pull the slide towards it. Finally, when the force has increased enough, the closed circuit of the magnetic flux inside the magnet is again closed. The object, which the magnet is used to grip, closes the circuit outside the magnet. If the electric current is still increased when the circuit of the magnetic flux is closed, the holding force may even be increased multifold. The permanent magnet part in connection with the movable slide may for example be neodymium magnetic material. Neodymium magnetic material is in this text often called the shorter name neodymium, according to one ingredient in it.

The magnetic field producing the holding force may be provided either only with a permanent magnet or both a permanent and an electric magnet. When electric current is fed through the coil of the electric magnet, the holding force cancels the magnetic field produced by the permanent magnet or strengthens it, depending on which direction the electric current is fed into the coil. The magnetic fields of the permanent magnet and the electric magnet may in a manner known as such be set to cancel out each other's effect or set to strengthen each other. In other words the magnetic field of the permanent magnet may be used to provide a holding force, which, if necessary, is weakened or strengthened with the magnetic field of the electric magnet and/or mechanically. By controlling the amount of electric current, the holding force of the magnet may thus be selected as desired. By switching off the electric current, the holding force does not cease, but the magnet remains holding. The weakening of the holding force of the magnetic fastener may be realised either mechanically by changing the magnetic circuit inside the attaching device or by weakening the field created by the permanent magnet with the electric magnet.

An advantage of the magnet according to the invention is that electric energy is needed only for altering the state of the magnet from the open position to the holding position and vice versa. In other words when the magnet is in the holding or open position, the magnet does not need electric energy.

In an embodiment of the invention the slide comprises a first slide part and a second slide part, between which the first permanent magnet is attached. The slide parts are attached in connection with the differently named poles of the permanent magnet. The first permanent magnet, the first slide part and the second slide part are advantageously round plates.

In an embodiment of the invention the slide is arranged to be movable, so that in the holding position of the magnet, the first slide part is in contact with the shell and the second slide part is in contact with the centre.

In an embodiment of the invention the coil of the electric magnet is arranged at least partly around the centre.

In an embodiment of the invention the centre comprises a second permanent magnet, which is arranged so that the differently named poles of the first and second permanent magnet are opposite to each other. Due to the second permanent magnet the magnetic circuit may efficiently be switched off.

In an embodiment of the invention the magnet comprises at least one spring, which is arranged to mechanically detach the slide from the shell and centre when the magnetic flux produced by the first permanent magnet weakens sufficiently due to the magnetic field produced by the electric magnet. In an embodiment of the invention one or more springs have thus been arranged between the movable slide and the other parts of the magnet. The springback factor of the springs is arranged to push the slide away from the rest of the magnet and to keep the slide away from the magnetic circuit. The springback factor is thus used to resist the permanent magnetic force. When the magnetic field generated with the electric magnet is used to weaken the permanent magnetic field, at a certain strength of the electric magnetic field, the springs have the strength to push the slide away from the other parts of the magnet. Thus the closed circuit breaks, the magnetic force weakens and the magnet is switched off, i.e. the hold of the magnet is off. When switching on such a magnet, the slide, to which the permanent magnet part is attached, starts to move, when the magnetic field is stronger than the springback factor of the springs. By means of said springs, the power need of the electric magnet may be adjusted. The springback factor of the springs manages a part of the switching off of the magnet, whereby the coil may be made smaller than what would be needed without the springs.

In an embodiment of the invention the magnet comprises a back plate, where the slide is arranged to be attached in the open position of the magnet. The attaching force may be adjusted to be suitable by altering the shape and/or metallicity of the back plate.

In an embodiment of the invention the magnet comprises at least one sliding sleeve, which is arranged to control the movement of the slide. The sliding sleeves are attached at their first ends to the back plate of the magnet and by their second ends to the shell, allowing movement of the slide between the holding and open position. The magnet advantageously has four sliding sleeves, which are arranged at the corners of the magnet. If the magnet comprises springs, they are advantageously arranged around the sliding sleeves.

In an embodiment of the invention the part of the slide meant to be inside the coil of the electric magnet has a constricted shape. The shape allows for the use of a larger permanent magnet and coil. Simultaneously the hold of the magnet is improved.

In an embodiment of the invention the edge of the shell meant to be in contact with the object to be gripped is bevelled to be thinner. The purpose of the bevelling is to increase the magnetic flux density at the contact surface and thus to improve the hold of the magnet. The direction of the bevelling may affect how well the magnet grips objects of different thicknesses.

In an embodiment of the invention the magnet comprises control means for controlling the magnetic field produced by the electric magnet. By controlling the strength of the magnetic field produced by the electric magnet, the slide of the magnet may be controlled. A slide comprising a permanent magnet makes it possible that the magnet does not during its normal operation continuously need an external power source. A relatively small power source, such as a battery, well suffices as the power source for an electric magnet functioning in a control purpose. It may be arranged as a fixed part of the magnet. The magnet may function completely wirelessly, and does thus not during normal operation need electric wires to its outside. The magnet may be controlled completely wirelessly, whereby the control electronics and the battery are inside the covers of the magnet. The control and/or power supply may also occur with wires, whereby a switch and/or a control unit is outside the magnet. The power supply may occur from a battery or another power source. The control electronics and/or the power source may be common for several magnets.

In an embodiment of the invention the magnet control means comprise an electric power source, such as a battery, and means for guiding the electric current in a controlled manner from the electric power source to the electric magnet in order to control its function.

In an embodiment of the invention the magnet comprises a wireless receiver for receiving a control signal from the control means.

An attaching device according to the invention comprises at least one magnet according to the invention, which is arranged to produce a holding force, and control means for controlling the holding force produced by the magnet.

The attaching device may be used to firmly grip for example another attaching device, an object to be worked and a working base. On the other hand, when desired, the attaching device is easy to detach from the other attaching device, the object to be worked and the working base. In the attaching device according to the invention the gripping of another attaching device, an object to be worked and a working base is done by means of the magnetic field produced with magnets. The attaching device has control means, by means of which the magnetic fields produced by the magnets may be controlled in order to make possible the gripping and detaching.

The controlling of the holding force of the magnets may be performed manually, for example by a switch or a lever in the attaching device. The connecting of electric current to the magnets may also be arranged to occur automatically, for example controlled by a computer program. It is possible to arrange one or more magnets to be used remotely. The remote use may be wireless. In an embodiment the remote use may be wired.

By controlling the strength of the magnetic field produced by the electric magnet, the holding force may be controlled. A slide comprising a permanent magnet makes it possible that the attaching device does not during its normal operation continuously need an external power source as a source for the holding force. A relatively small power source, such as a battery, well suffices as the power source for an electric magnet functioning in a control purpose. It may be arranged as a fixed part of each separate attaching device. Such an attaching device may function completely wirelessly, and does thus not during normal operation need electric wires to its outside.

In an embodiment of the invention the holding force is controllable, so that in connection with attaching the object, the holding force of the magnet of the attaching device is increased in steps or degrees. In an embodiment of the invention the holding force is controllable, so that in connection with detaching the object, the holding force of the magnet of the attaching device is decreased in steps or degrees. In an embodiment of the invention the holding force may be increased if it is detected that the magnet is detaching. A magnet, which is about to detach, may be detected for example by monitoring the position of the slide.

In an embodiment of the invention the control means are arranged to control the magnetic field produced by the electric magnet of the magnet.

In an embodiment of the invention the control means comprise an electric power source, such as a battery, and means for guiding the electric current in a controlled manner from the electric power source to the magnet in order to control its function.

In an embodiment of the invention the control means are arranged so that the magnets are separately controllable.

In an embodiment of the invention the attaching device comprises a wireless receiver for receiving a control signal from the control means.

In an embodiment of the invention the attaching device comprises a sensor, which is arranged to sense if the attaching device is attached to an object.

In an embodiment of the invention a tight fold, for example a rubber fold, is attached to the edge of the shell meant to be in contact with the object to be gripped, which fold is arranged to seal the gripping point between the magnet and the object to be gripped. By arranging an underpressure in the gripping point via the shell of the magnet, the magnet may also be used to grip non-magnetic objects.

An attaching device according to the invention comprises a first magnet according to the invention in the first end of the attaching device, which first magnet is arranged to produce a first holding force for attaching the attaching device to a working base or another attaching device or an object to be worked, a second magnet according to the invention in the second end of the attaching device, which second magnet is arranged to produce a second holding force for attaching the attaching device to the working base or another attaching device or an object to be worked, and control means for controlling the holding forces produced by the first and second magnet.

The attaching device may have one, two or more controllable magnets. The attaching device may also have one or more other holding means. The other holding means may for example be some mechanical holding means, such as a clamp, a suction cup or pliers. The attaching device may for example have one magnet and one other holding means. Typically the attaching device has at least two such holding means, the holding force of which can be controlled. The other holding means are known as such, so their operation is not described further in this text.

In an embodiment of the invention the control means are arranged so that the first and second magnet are separately controllable. In an embodiment of the invention the second magnet is controlled manually from a lever or switch in the attaching device or remotely. In an embodiment of the invention one of the magnets is controlled manually and one automatically. Thus the same attaching device is suitable for different use purposes and situations.

In an embodiment of the invention an insulation insulating from the magnetic flux is arranged between the first and the second magnet, such as a plate manufactured from fibreglass or another material insulating the magnetic flux. Other suitable materials may for example be aluminium, plastic, acid resistant steel and glass. Thus the operation of one magnet does not disturb the operation of the other magnet.

In an embodiment of the invention the magnets are insulated to be waterproof. In an embodiment the magnets are cast into a suitable hardening material, for example polyester resin. Waterproofness is sometimes important, because workings often use liquids, which may otherwise cause a short circuit in the electric devices.

In an embodiment of the invention, the attaching devices according to the invention are used under water. In an embodiment of the invention the entire attaching device is insulated to be waterproof. Attaching devices according to the invention, which are waterproof, especially those which are waterproof and may be used remotely, are especially well suited for working under water.

In an embodiment of the invention the control means comprise in the attaching device means for leading the electric current in a controlled manner from an electric power source to the first and/or second magnet in order to control its function.

In an embodiment of the invention the control means comprise an electric power source, such as a battery, and means for guiding the electric current from the power source to the first and/or second magnet. In other words the attaching device thus has its own electric power source, such as battery.

In an embodiment of the invention the attaching device comprises a wireless receiver for receiving a control signal from the control means. The arrangement according to the invention thus comprises a wireless transmitter. When using wireless attaching devices, electric wires may be avoided. In an embodiment of the invention the attaching device comprises a wireless transmitter for transmitting information, such as operation data of the attaching device, temperature, detaching of the magnet etc. data from the attaching device for example to a control unit outside the attaching device.

In an embodiment according to the invention the control means of the attaching device comprise a wireless receiver and/or transmitter in order to transmit control data.

In an embodiment according to the invention the attaching device functions completely wirelessly in normal use. In other words the electricity needed by the attaching device is charged wirelessly and the data transfer to the attaching device and from it is performed wirelessly.

In an embodiment according to the invention the control means of the attaching device comprise control devices for the electric magnet of the attaching device.

In an embodiment of the invention the attaching device comprises at least in its one end a mechanical attaching means, such as a hook, spike, bolt or peg. The first or second magnet may thus be arranged to move said mechanical attaching means. The mechanical attaching means may also be moved by hand. Such an attaching device may be arranged to attach to a working base or object to be worked manufactured from any material, also a non-magnetic material.

The mechanical attaching means may also function as a movement limiter or a limit switch. The automatism controlling the arrangement may be arranged to place said limiters or limit switches precisely in the desired places of the object to be worked. The mechanical limiters or limit switches may for example be placed in intended places on the edges of the object to be worked. When such limiters or limit switches are in place, the object to be worked is easy to place correctly according to them.

In an embodiment of the invention the attaching device comprises a frame, in the different ends of which the first and second holding means, such as the magnet, is attached. The frame may for example be tube-like or cubic.

In an embodiment of the invention the frame of the attaching device is manufactured from stainless steel and in another embodiment from fibreglass.

In an embodiment of the invention the frame of the attaching device comprises means for selecting its length as desired. The frame may for example be telescopic. The frame may have a locking device, such as a clamp, for locking the length of the attaching device as desired. The locking of the length may also be done with a permanent magnet. Thus the same attaching device is suitable for different use purposes and situations.

In an embodiment of the invention the frame of the attaching device comprises means for bending it into a desired position. The frame may for example consist of two parts, which are joined together with a hinge or joint, for example with a ball joint. The frame may have a locking device, such as a clamp, for locking the position as desired. The locking of the position may also be done with a permanent magnet. Thus the same attaching device is suitable for different use purposes and situations.

In an embodiment of the invention the frame of the attaching device comprises several hydraulic cylinders, for example one in each corner of the frame. A magnet valve or the like may be used to control the passage of hydraulic fluid into the cylinders. When the fluid can flow, the length of the hydraulic cylinders may be changed. If the length of all of the hydraulic cylinders is changed by the same amount, the length of the frame changes, but the ends of the attaching device, their holding devices, do not turn in relation to each other. If, on the other hand, the lengths of the hydraulic cylinders are changed in different ways, the attaching device bends. In other words the ends of the attaching device, their holding means, turn in relation to each other. By closing the magnet valve or the like, the valve can be locked into place.

An attaching arrangement according to the invention comprises at least one attaching device according to the invention, a control unit for producing control signals for the magnets of the attaching devices, and data transfer devices for transmitting the control signals to the control means of the attaching devices.

One or more attaching devices according to the invention may be used for attaching the object to be worked to a working base. The arrangement comprises a control unit, such as a programmable computer and its user interface for producing control signals to the magnets of the attaching devices. The control unit may be separate from the attaching devices. The arrangement also comprises data transfer devices for transmitting the control signals to the control means of the attaching devices. The data transfer devices may be wireless and they may use some known data transfer method, such as radio, light, sound or the like.

Some embodiments of the arrangement comprise a robot or a corresponding NC-programmable device, which comprises means for placing the attaching devices in desired places for example on the working base or attached to other attaching devices.

A machined metal plate or other magnetic substance may for example function as the working base. The system may also itself function as its own working base, i.e. the system may assemble a working base from itself. The jig may also be assembled completely without a particular working base.

An arrangement according to the invention may have a charging device, whereto the attaching devices are connected when they are not doing attaching work. The attaching device thus has the necessary means, for example connectors and cables or means enabling wireless charging, by means of which the electric power source is connectable to the attaching device. When using wireless attaching devices, electric wires may be avoided.

The charging device according to the invention may also be arranged to function as a parking device for the attaching device.

In a typical method according to the invention for attaching to an object the attaching device according to the invention is attached to the object by means of the holding force produced by a magnet.

In an embodiment of the invention the slide is moved in relation to the shell and centre, in order to close and open the circuit of the magnetic flux, i.e. in order to alter the state of the magnet between a holding position and an open position, the slide is held in connection with the shell and centre with the magnetic field of the first permanent magnet, when the circuit of the magnetic flux is closed, i.e. when the magnet is in the holding position, and the magnetic flux provided by the first permanent magnet is at least partly switched off, when necessary, by producing a magnetic field with an electric magnet, in order to change the state of the magnet to the open position.

In an embodiment of the invention a force is produced with at least one spring, which force strives to mechanically detach the slide from the shell and centre when the magnetic flux produced by the first permanent magnet weakens sufficiently due to the magnetic field produced by the electric magnet.

In an embodiment of the invention movement of the slide in relation to the rest of the magnet is monitored with a sensor, and if movement is detected when the magnet is in the holding position, the holding force of the magnet is increased by giving more electric current to the electric magnet coil.

A sensor, which gives information to the processor if the slide strives to move when the magnet should be in the holding position, may be placed in the movable slide, for example in the back plate. In the holding position the slide moving in relation to the rest of the magnet would mean that the magnet is detaching. Thus the processor may increase the holding force of the magnet by giving more current to the coil in the suitable direction, which strengthens the magnetic flux. Such an active monitoring of the hold and increase in strength as needed is important, in order for the system to be reliable. Information about the hold or detachment of the magnet may be conveyed to a user or the system which the magnet belongs to. Real-time information about the hold is needed for example when welding, cutting and in corresponding situations. Thus real-time monitoring of the state of different fasteners, for example those used in laser welding, becomes possible.

By means of the invention a work machine, such as a robot, may assemble a lifting device of a required shape for itself for object handling from attaching devices according to the invention and possible additional pieces.

In one embodiment of the invention the magnet, i.e. its movable slide, is guided between the holding position and the open position with electric current pulses led into the coil. The duration of the pulse may for example be about half a second or 0.1-1 seconds.

In the holding position the electric current pulse switches off the magnetic flux to the extent, where the springs move the slide away from the rest of the magnet and thus open the closed circuit of the magnetic flux. The magnet thus moves to the open position. The open position is changed to the holding position with an opposite pulse, which increases the magnetic flux, so that the slide moves into connection with the rest of the magnet, whereby the circuit of the magnetic flux again closes.

The movement of the magnet parts may be controlled in a controlled manner for example with the aid of a processor by giving the coil for example a PWM signal (Pulse Width Modulation). The control may occur also by changing the level of the current. For example a pulse with a 10 second total duration may consist of a 0.5 second part, when the signal is on, and a 0.1 second part, when the signal is off.

The different embodiments of the invention are suitable for use in connection with various kinds of substances and working methods. The invention may be used for example for bevelling, flame cutting, laser cutting, water cutting, plasma cutting, pipe cutting, welding, milling, machining, pressing, painting, sandblasting, burring, drilling and for temporarily attaching parts to each other.

By means of the invention, the attaching of the object to be worked to its base may simply be automated. It is possible to program a robot to place the attaching devices in desired places on the working base. The programming and designing of the robots and automatism are not especially an object of this application, so they are not discussed further in this context.

Suitable dimensions of the magnets and required electric currents and materials may be selected separately for each situation. For example in some cases, one must be careful that the permanent magnet is not demagnetised, if this is not the purpose.

The permanent magnetic parts of the magnet may be implemented from different magnetic materials, such as AlNiCo, so-called rare-earth magnets such as neodymium magnets (i.e. a NdFeB, NIB or Neo magnet) or a ceramic magnetic material. For example the AlNiCo magnetic material is suitable as a demagnetisable and re-magnetisable magnetic material. AlNiCo is a metal alloy, which is manufactured from aluminium (Al), nickel (Ni) and cobalt (Co). There may additionally be iron, copper and titanium in the alloy. A typical alloy ratio is 8-12 Al, 15-26% Ni, 5-24% Co, max. 6% Cu and 1% Ti, the rest is Fe. For example NdFeB and/or a ceramic magnetic material may be used as the permanent magnetic material. A neodymium magnet is a rare-earth magnet, an alloy of neodymium, iron and boron. A ceramic magnet is a magnet manufactured with powder-metallurgic methods, which has large amounts of metal oxides. For example ceramic ferrite is a ferromagnetic ceramic material, which has iron oxide, boron and barium or strontium or molybdenum. Some examples of suitable magnetic materials are AlNiCo 5, NdFeB 40 MGOe and Ceramic 8. The first permanent magnet is advantageously manufactured from neodymium and the second permanent magnet from AlNiCo material.

Depending on the used magnetic material and the need at the time, the outer dimensions of the magnetic clamp vary. The slide may be formed for example to be cylindrical. The diameter of the cylindrical slide may for example be less than 200 mm, less than 100 mm, less than 50 mm, 25-200 mm, 25 or 50-100 mm. The height of the slide may for example be less than 100 mm or less than 50 mm or less than 10 mm or 25-100 mm or 1-25 mm or 0.5-3 mm. In order to improve the hold, the diameter of the slide may for example be 10-30% larger than the centre.

The attaching device according to the invention may be seen as one embodiment of the magnet with controllable power according to the invention. In an advantageous embodiment the magnet is switched off and on partly mechanically by moving the parts of the magnet in relation to each other. The magnet according to the invention has a slide comprising a permanent magnet part, which is arranged to be movable in relation to the rest of the magnet, which slide may be arranged at least partly inside the coil. One or more springs may in a manner described above have been arranged between the slide and the rest of the magnet.

In an embodiment of the invention the magnet is used as a so-called bistable magnet. Only a small amount of energy is needed to open and close a bistable magnet. Bistable magnets can be kept switched on and switched off without using electric energy. Thus the arrangement according to the invention may be used to decrease the amount of electric energy consumed in the process.

In an embodiment of the invention the magnet functions as an electrically controllable shock absorber, which may simultaneously also be used to produce energy. The magnetic field of the coil may be used to decelerate the movement of the slide moving inside the coil. If for example a slide comprising neodymium is moved inside the coil, electric current is generated in the coil. This is thus a generator, which produces electric energy.

The magnet according to the invention may be used in applications moving along metal surfaces. Examples of such applications are for example means for washing the bottoms of ships, and various other robots, such as welding and painting robots. In these applications the apparatus is moved along the metal surface and thus they need a strong, firmly holding magnet. Such a magnet is advantageously also controllable with a low amount of energy.

The magnet according to the invention may also be used for controlling magnetic valves and magnetic locks at least between an open position and a closed position. Magnetic valves and magnetic locks according to existing technology require energy for keeping them switched on or off, while the embodiment according to the invention needs energy only for changing the state.

The magnet according to the invention may be used for controlling movement, because the slide is arranged to be moving. This movable slide may be moved with a small pulse, whereby the springs are released, and a movement is generated, which always remains in its extreme position to await a new pulse.

The magnet according to the invention may be used for demagnetising objects. This is done so that the magnet is placed in contact with the object to be demagnetised and electric current is fed into the electric magnet. The slide is typically locked for the duration of the demagnetisation process.

A magnet/attaching device according to the invention may also be attached in a fixed manner, in other words without a magnet, to some object. The attaching manner may for example be a fixed screw connection or a bayonet connection occurring with a catch, and the attaching target may for example be a lifting device, a jig or a fire door. Attaching occurring by means of electricity may also be used, attaching occurring by means of hydraulics or pressurised air is also possible. Attaching is also possible with a second magnet. The attaching can also be done with a crimp connection. Fixed attachment of the magnet/attaching device is used especially when the power supply occurs with conductors. In situations where it is necessary to charge the batteries of the magnet, different quick attachment methods may turn out to be practical.

In an embodiment of the invention the attaching device is used for lifting metallic parts, such as metal plates, from a pile.

BRIEF DESCRIPTION OF THE FIGURES

The invention is described in more detail below with reference to the enclosed schematic drawing, in which

FIG. 1 shows an attaching device according to the invention,

FIG. 2 shows the attaching device of FIG. 1 taken apart,

FIG. 3 shows a second attaching device according to the invention,

FIG. 4 shows the attaching device of FIG. 3 taken apart,

FIG. 5 shows an opened magnet according to the invention,

FIG. 6 a shows a partial cross-section of a detail of a third attaching device according to the invention,

FIG. 6 b shows a partial cross-section of a detail of a fourth attaching device according to the invention,

FIGS. 7 a, 7 b and 7 c show simulations of a magnetic flux in the attaching device according to the invention,

FIG. 8 shows an arrangement according to the invention,

FIG. 9 shows an attaching device according to the invention, where two lever pliers have been attached,

FIG. 10 shows a charging mount for attaching devices according to the invention,

FIG. 11 shows a work station,

FIG. 12 shows a second magnet according to the invention,

FIG. 13 shows the magnet of FIG. 12 taken apart,

FIG. 14 shows a cross-section of the magnet of FIG. 12 in a holding position, and

FIG. 15 shows a cross-section of the magnet of FIG. 12 in an open position.

DETAILED DESCRIPTION OF THE EXAMPLES OF THE FIGURES

For the sake of clarity, the same reference numbers are used for at least some corresponding parts in different embodiments.

In the middle of the mainly cylindrically formed attaching device 10 shown in FIGS. 1 and 2 there is a frame 3 manufactured from a suitable material, such as fibreglass or some other material, which lets through an RF signal. If the control signal of the attaching device is something other than an RF signal, for example light, the material of the frame may be some other material suitable for the purpose. The other parts of the attaching device are supported on the frame or they are arranged inside it or joined together with screws. In the lower edge of the device 10 there is a first magnet 8, which is meant for attaching the device 10 to a working base. In the upper edge of the device 10 there is a second magnet 1, which to its structure corresponds to the first magnet 8, which second magnet is meant for attaching the device 10 to an object to be worked.

The magnet 1 comprises a shell 19 and a centre 22, between which an electric magnet part 11, i.e. an electric magnet, is arranged. The coil of the electric magnet 11 is drawn in the figure very schematically with dotted lines 12. A battery 6 and two circuit boards 2 and 7 have been arranged inside the frame 3, between the first and second magnet. The frame 3 has a service hatch 5 that can be opened, which leads though the frame, for example to enable the changing of the battery 6. Led lights have also been arranged through the frame, which may be used to indicate for example the charge state of the battery 6 or if the battery is charging. The leds may also be used to indicate for example if the first or second magnet is switched on or off.

In the lower i.e. first circuit board 7 there is for example control electronics for the electric magnets 11, a thermometer, and a charging device for the battery 6. In the upper i.e. second circuit board 2 there is a radio transmitter/receiver for transmitting control information and operation information of the attaching device 10 between the attaching device 10 and the control unit outside it.

FIGS. 3 and 4 show an attaching device 10, which to its shape mainly is a cubic or rectangular prism. The upper magnet 1 is attached to the rest of the device with attaching screws 13. The lower magnet 8 is attached to the rest of the device with attaching screws 14. Between the upper magnet 1 and lower magnet 8 there is a frame 3. Inside the frame 3 has been arranged connection pipes 15 supporting the structure, by means of which the upper magnet 1 is connected to the lower magnet 8. Among others a circuit board 2 is placed between the connection pipes, in the so-called frame part. Electric components needed by the device, such as selection switches 16, are attached to the circuit board 2, by which switches the operation of the attaching device 10 may be controlled manually. From the selection switches 16 the magnets 1 and 8 may for example be switched on and off. They may additionally be used to give commands to switch off the attaching device 10 or to activate a switched-off attaching device 10. The selection switches 16 may have one or more led indicators, from which different information about the magnet state may be seen, such as “open” or “closed” or “system failure”.

Batteries 7 have also been attached to the circuit board 2, and electric charging connectors 17 for bringing charging current for the batteries from the charging device. The charging connectors 17 may for example also be strip-like. Openings 18 have been formed in the frame 3 for using the selection switches 16. There are also openings for the charging connectors 17 in the frame (not shown).

Among others components needed for communication, such as an RF transmitter and receiver, sensors monitoring the state of the magnet and a processor, the software in which manages among others data communications, interruptions in the operation and alarms, are also attached to the circuit board 2. The communication may for example be the direct two-way communication with a device controlling the attaching device 10, i.e. a so-called Interface, or the forwarding of a message to another attaching device and/or Interface. An interruption of the operation may be caused for example by the state of the magnet 1 or 8, the temperature or a weakening in the charging level of the battery or other anomaly. The interruptions in operation may for example be set as limit values of the program controlling the attaching device, the surpassing of which causes an interruption.

FIG. 5 shows a magnet 8 according to the invention taken apart. For example the lower magnet 8 shown in FIGS. 3 and 4 may have the structure shown in FIG. 5. The upper magnet 1 in FIGS. 3 and 4 may have a corresponding structure. The slide 30 of the magnet comprises a back plate 23, a neodymium magnet 24 and a front plate 25 attached together. The attaching screws 26 of the pushing plates attach the pushing plates 27 to the back plate 23. Stopper screws 31 hold the parts of the magnet 8 together. The slide is arranged to be movable in relation to the rest of the magnet 8. When the slide is in the lower position it settles partly inside the coil 29 of the electric magnet. The pushing springs 32 are arranged around the stopper screws 31 so that they strive to push the slide 30 upwards, i.e. away from the coil 29 and the centre 22. The pushing springs 32 thereby help the coil 29 to switch off the magnet 8 and to keep the magnet 8 switched off. For example if the coil 29 does not switch off the magnet 8 completely, but the pushing springs 32 can already push the slide 30 away, the magnet is switched off by the co-operation between these. The pushing plates 27 centre the slide 30 into place and relay the pushing force of the springs 32 to the slide.

The object, which the magnet 8 in FIG. 5 grips, is placed against the lower surface of the magnet 8. Brass plates 20 and 21 have been arranged at the bottom inside the shell 19 of the magnet, and a centre 22 between them. The centre 22 is attached with the outermost brass plate 20 to the shell 19, so that the magnet 8 does not have moving parts, which can be seen from the outside. The smaller brass plate 21 is attached to the centre 22, whereby the lower surface of the magnet is even. In its lower position the slide 30 touches the centre 22, whereby the magnetic flux can pass to the object to be gripped. When the slide 30 is lifted up, the passage of the magnetic flux to the object to be gripped is prevented. The shell 19 of the lower magnet functions as a part which conducts the magnetic flux. Correspondingly the shell 47 of the upper magnet seen in FIGS. 3 and 4 functions as a part, which conducts the magnetic flux in the upper magnet 1. The brass plates 20 and 21 isolate the magnetic flux so that it cannot leak from the shell 19 to the slide 30. In the lower edge of the shell 19 there is a bevelling 28, which is meant to be in contact with the object to be gripped. The bevelling 28 guides the magnetic flux in order to achieve a greater holding force and increases the surface adhesion of the magnet. Thus due to the bevelling 28, the magnet holds well also with a thin plate.

The front plate 25 narrows towards the bottom. Thus the slide 30 is constricted, i.e. tapered. A larger coil 29 may be arranged around the constricted slide 30. A larger coil 29 makes possible the use of a larger effect, whereby a larger permanent magnet may in turn be used, such as a neodymium magnet 24. By means of the constricted slide a greater holding force is thus achieved than without the constriction.

FIG. 6 a shows a partial cross-section of a detail of a third attaching device according to the invention. FIG. 6 b shows a partial cross-section of a detail of a fourth attaching device according to the invention. An object 33, which the magnet is meant to grip, is drawn to be visible in FIGS. 6 a and 6 b. A back plate 23, a shell 19, a neodymium magnet 24, a front plate 25, an electric magnet coil 29 and a centre 22 are seen in the figures. The back plate 23, neodymium magnet 24 and the front plate 25 attached together form a movable slide 30. The difference between FIGS. 6 a and 6 b is that the surfaces of the slide 30 and the rest of the magnet, i.e. the shell 19 in the figures, are vertical in FIG. 6 b in the contact spot 34, i.e. in the direction of the movement of the slide. In FIG. 6 a the corresponding surfaces in the contact spot 34 are slanted in relation to the movement of the slide 30. By means of the solution in FIG. 6 b the opening and closing of the circuit of the magnetic flux is more efficient in some situations.

FIGS. 7 a, 7 b and 7 c show simulations of the magnetic flux in the magnet 8 of an attaching device according to the invention. FIG. 7 a shows just a simulation model when the slide 30 is in the lower position, i.e. the magnet is in the holding position. In FIG. 7 b the situation is the same as in FIG. 7 a, but the simulated passage of the magnetic flux is drawn in the figure with lines. In FIG. 7 c the slide 30 is lifted away from the rest of the magnet i.e. the shell 19. The magnet is thus in the open position. From the figures can be seen how the passage of the magnetic flux breaks in the open position.

FIG. 8 shows an arrangement according to the invention for attaching an object to be worked to the working base. The arrangement comprises a control unit i.e. an interface 35, and three identical attaching devices 10, 10′ and 10″ according to the invention. The control unit 35 transmits messages from the controlling system (not shown) to the attaching device. The control unit has a so-called I/O inlet and it may be controlled for example with a 5V, 12V or 24V voltage. The controlling system may be a robot (see FIG. 12), a welding device, a cutting device or another corresponding programmable device. In the program, which may be run on the processor of the control unit 35, it has in advance been defined what should be done when as certain I/O command arrives. The I/O may for example be 8, 16, 32 or 64-bit.

The robot for example gives a command [32] to the control unit. It may for example mean “Open the upper magnet of the attaching device”. The control unit reads the command [32] in its inlet ports. The information that the MAC address of the upper magnet of the attaching device 10 is 54321 has been programmed into the software in advance. Thus the control unit sends the command [32] to the address 54321. The software in the processor in the attaching device 10 knows that when the command [32] arrives, the upper magnet should be opened. The attaching devices in the system may be identical. Only their MAC addresses are individual. The MAC addresses of the attaching devices are programmable with the control unit, so any available attaching device 10, 10′ or 10″ may receive the command, as long as the attaching device is programmed into the system. Thus the program in the robot does not need to be changed, even if one of the attaching devices were to be out of use. There may be several, even hundreds of cubes in the system at the same time.

Various tools, which assist in gripping the objects 33 to be worked, may be connected to the attaching device 10 according to the invention. FIG. 9 shows an attaching device 10, where two lever pliers 39 have been attached.

FIG. 10 shows the charging mount 40 for attaching devices according to the invention, which has six places 41 for an attaching device. The attaching devices 11 are stored in the charging mount when they are not needed. The mount has a charging device (not shown), which has charging means suitable for the attaching devices 10, such as connectors suiting the charging connectors 17 seen in FIGS. 3 and 4. The battery of an attaching device 10 in the mount may thus be charged. The edges 42 of the places for the attaching devices advantageously also position the cube when it is set in the mount.

FIG. 11 shows the working place of a robot 43, where an arrangement according to the invention is used. The working place has eighteen attaching devices 10 and a charging mount 40 for them, which is placed in a tool mount 44. The metallic work surface 45 is empty. The robot has a magnetic tool 46, with which it takes the attaching devices from the charging mount 40 and places them on the work surface 45. When it has assembled a desired jig from the attaching devices 10, it places the object to be worked in the jig, changes the tool and starts the working.

The operation of an embodiment of the invention may for example be described as follows. An electric current of a desired magnitude is guided to the coil 29 based on the software executed with the processor on the circuit board 2 of the attaching device 10. When current is led to the coil in a certain direction, the magnetic field produced by the coil weakens the magnetic field of the permanent magnet 24. At a certain strength of the magnetic field the movable slide 30 moves away from the rest of the magnet. The detaching occurs for example when the strings 32 have the strength to push the slide 30 away from the frame, into the open position. Thus the magnetic flux cannot pass, the magnetic force weakens and the magnet is switched off, i.e. the hold of the magnet is off. When the hold of the lower magnet 8 is off, it can be placed on the metal of the work surface 45 or on another attaching device. Thereafter a current is led into the coil 29 in the opposite direction to when the hold was detached. The electric current is thus guided in the direction of the coil, which strengthens the magnetic field of the permanent magnet 24. Now the magnetic field of the coil starts to pull the permanent magnet part 24 towards it. In the end, for example when the magnetic field is stronger than the springback factor of the springs 32, the slide 30 starts to move toward the holding position. Finally, when the force has increased enough, the circuit of the magnetic flux is again closed. Thus the magnet receives more holding force. The permanent magnet part 24 may for example be neodymium magnet.

The operation of an embodiment of the invention, where a robot controls the arrangement, may be described as follows. The control unit 35 receives from the robot 43 the command “Open the upper magnet 1 of the attaching device 10”. The control unit 35 transmits the message to the attaching device 10. The attaching device 10 receives the message and opens its upper magnet 1 according to the command. When the upper magnet has opened the attaching device 10 in turn sends a message to the control unit 35, observes it, and forwards it to be read by the robot 43 to the I/O port of the control unit: “The upper magnet 1 of the attaching device 10 is open”. The robot may thus verify that the message has been received and the command has been realised.

The operation of another embodiment of the invention, where a robot controls the arrangement, may be described as follows. The control unit 35 receives from the robot 43 the command “Open the upper magnet 1 of the attaching device 10”. The control unit 35 transmits the message to the attaching device 10. If the attaching device 10 does not respond to the message within a certain time frame, the control unit 35 tries again. If the attaching device 10 still does not answer, the control unit 35 gives a forwarding command. The control unit 35 has information in its memory regarding which attaching devices the system has in use and it requests the nearest other attaching device to forward the message. Now the attaching device 10′ receives a request to forward a message and forwards the message to the attaching device 10. The attaching device 10 opens its upper magnet and responds to the attaching device 10′ “The upper magnet 1 of the attaching device 10 is open”. The attaching device 10′ forwards the message to the control unit 35 and this forwards it to the robot 43. Thus the message has been received and the command has been acknowledged. The system functions like this itself and the user does thus not need to separately observe that the message is received. Any attaching device of the system may function as the transmitter to any other attaching device in the system. It is also possible to program corresponding programs in the processor of the attaching device as into the control unit 35, whereby the attaching device itself may function as a controller of others, without a separate control unit 35.

FIG. 12 shows a magnet according to an embodiment of the invention and FIG. 13 shows the same magnet taken apart. The magnet 8 comprises a shell 19 and a centre 22, and a slide 30 arranged to be movable in relation to them. The slide 30 comprises a back plate 23, a neodymium magnet 24 and a front plate 25 attached together. The centre 22 comprises an AlNiCo magnet (not seen in FIGS. 12 and 13), which is arranged so that the differently named poles of it and of the neodymium magnet 24 are opposite to each other.

The attaching screws 26 of the pushing plates attach the pushing plates 27 to the back plate 23. The pushing plates 27 are arranged in connection with the sliding sleeves 51, so that the slide 30 can move as controlled by the sliding sleeves 51. The slide 30 is thus arranged to be movable in relation to the rest of the magnet 8. When the slide 30 is in the lower position it settles partly inside the coil 29 of the electric magnet. The pushing springs 32 are arranged around the sliding sleeves 51 so that they strive to push the slide 30 upwards, i.e. away from the coil 29, the centre 22 and the shell 19. The pushing springs 32 thereby help the coil 29 to switch off the magnet 8 and to keep the magnet 8 switched off. For example, if the coil 29 does not switch off the magnet 8 completely, but the pushing springs 32 can already push the slide 30 away, the magnet 8 is switched off by the co-operation between these. The pushing plates 27 centre the slide 30 into place and relay the pushing force of the springs 32 to the slide 30.

The magnet 8 comprises a rear plate 53, which simultaneously functions as an attaching plate for the magnet 8. Screws 52 hold the parts of the magnet 8 together via the sliding sleeves 51. The screws 52 are attached to the ends of the sliding sleeves 51. A platform plate 54 has been installed between the rear plate 53 and the shell 19. The control electronics needed by the electric magnet is integrated into a circuit board 55.

The object, which the magnet 8 in FIG. 12 grips, is placed against the lower surface of the magnet 8. In its lower position the slide 30 touches the shell 19 and the centre 22, whereby the magnetic flux can pass to the object to be gripped. When the slide 30 is lifted up, the passage of the magnetic flux to the object to be gripped is prevented. The shell 19 and centre 22 of the magnet function as parts guiding the magnetic flux.

The magnet 8 shown in FIG. 12 may be attached with attaching screws 56 for example to a working base or another corresponding object.

The operating principle of the magnet shown in FIG. 12 is presented in more detail with the aid of a cross-section of the magnet in FIGS. 14 and 15. FIG. 14 shows the magnet in a holding position and FIG. 15 in an open position.

In the holding position of the magnet 8 the slide 30 is in the lower position. Thus the back plate 23 of the slide 30 is in contact with the shell 19 and the front plate 25 is in contact with the centre 22. The neodymium magnet is attached between the back plate 23 and the front plate 25. The slide 30 stays in contact with the shell 19 and centre 22 with permanent magnetic force, maintaining the part of the closed circuit of the magnetic flux, which is inside the magnet 8. The object 33, to which the magnet is attached, forms the part of the closed circuit of the magnetic flux, which is outside the magnet 8. The parts of the shell 19 and centre 22 which are in contact with the object 33 form the differently named poles of the magnet 8. The centre 22 contains an AlNiCo magnet 57.

When the magnet 8 is arranged in the open position, the slide 30 is in the upper position. The slide 30 is thus detached from the shell 19 and the centre 22, as a result of which the circuit of the magnetic flux is no longer closed.

The figures show only a few preferred embodiments according to the invention. Facts of secondary importance with regards to the main idea of the invention, facts known as such or evident for a person skilled in the art, such as electric cables, data communication devices or support structures possibly required by the invention, are not separately shown in the figures. It is obvious to someone skilled in the art that the invention is not limited merely to the above-described examples, but the invention may vary within the scope of the claims presented below. The dependent claims present some possible embodiments of the invention, and they are as such not to be considered to restrict the protective scope of the invention. 

1-21. (canceled)
 22. A magnet, which comprises: a first permanent magnet for creating a magnetic field, a shell and a centre, which are arranged to guide a magnetic flux to an object to be gripped, a slide, which is arranged to be movable in relation to the shell and the centre, which slide comprises said first permanent magnet, and an electric magnet for moving the slide, a coil of the electric magnet being arranged at least partly around the centre and attached to the shell.
 23. The magnet according to claim 22, wherein the slide comprises a first slide part and a second slide part, between which the first permanent magnet is attached.
 24. The magnet according to claim 23, wherein the slide is arranged to be movable, so that in the holding position of the magnet, the first slide part is in contact with the shell and the second slide part is in contact with the centre.
 25. The magnet according to claim 22, wherein the centre comprises a second permanent magnet, which is arranged so that the differently named poles of the first and second permanent magnet are opposite to each other.
 26. The magnet according to claim 22, wherein the magnet comprises at least one spring, which is arranged to mechanically detach the slide from the shell and the centre when the magnetic flux produced by the first permanent magnet weakens sufficiently due to the magnetic field produced by the electric magnet.
 27. The magnet according to claim 22, wherein the magnet comprises at least one sliding sleeve, which is arranged to control the movement of the slide.
 28. The magnet according to claim 22, wherein a part of the slide meant to be inside the coil of the electric magnet has a constricted shape.
 29. The magnet according to claim 22, wherein an edge of the shell meant to be in contact with the object to be gripped is bevelled to be thinner.
 30. The magnet according to claim 22, wherein the magnet comprises control means for controlling the magnetic field produced by the electric magnet.
 31. The magnet according to claim 30, wherein the control means comprise a source of electric power, such as a battery, and means for guiding electric current in a controlled manner from the electric power source to the electric magnet in order to control its function.
 32. The magnet according to claim 30, wherein the magnet comprises a wireless receiver for receiving a control signal of the control means.
 33. An attaching device, which comprises: at least one magnet according to claim 22, which magnet is arranged to produce a holding force, and control means for controlling the holding force produced by the magnet.
 34. The attaching device according to claim 33, wherein the control means are arranged to control a magnetic field produced by the electric magnet of the magnet.
 35. The attaching device according to claim 33, wherein the control means are arranged so that the magnets are separately controllable.
 36. An attaching device, which comprises: a first magnet in the first end of the attaching device, which first magnet is arranged to produce a first holding force for attaching the attaching device to a working base or to another attaching device or to an object to be worked, a second magnet in the second end of the attaching device, which second magnet is arranged to produce a second holding force for attaching the attaching device to the working base or to another attaching device or to the object to be worked, and control means for controlling the holding forces produced by the first and second magnet; wherein the first and/or second magnet is a magnet according to claim
 22. 37. An attaching arrangement, which comprises: at least one attaching device according to claim 22, a control unit for producing control signals for the magnets of the attaching devices, and data transfer devices for transmitting the control signals to the control means of the attaching devices.
 38. A method for attaching to an object, which method comprises: attaching an attaching device according to claim 22 to an object by means of a holding force produced by a magnet.
 39. The method according to claim 38, comprising: moving a slide in relation to a shell and centre, in order to close and open a circuit of the magnetic flux, i.e. in order to change the state of the magnet between a holding position and an open position, holding the slide in connection with the shell and centre with a magnetic field of the first permanent magnet, when the circuit of the magnetic flux is closed, i.e. when the magnet is in the holding position, and switching off the magnetic flux provided by the first permanent magnet at least partly, when necessary, by producing a magnetic field with the electric magnet, in order to change the state of the magnet to the open position.
 40. The method according to claim 38, comprising: producing a force with at least one spring, which force strives to mechanically detach the slide from the shell and centre when the magnetic flux produced by the first permanent magnet weakens sufficiently due to the magnetic field produced by the electric magnet.
 41. The method according to claim 38, comprising: monitoring movement of the slide in relation to the rest of the magnet with a sensor, and if movement is detected when the magnet is in the holding position, increasing the holding force of the magnet by giving more electric current to the electric magnet coil. 